Treatment results of non-Hodgkin lymphoma (NHL) in children has been shown in this study. From 1979 to 2003 children were registered with the diagnosis of NHL in oncology centers of Polish Pediatric Leukaemia/Lymphoma Study Group, a group of 397 patients with NHL B, 222 pts with NHL T and 54 pts with anaplastic large cell lymphoma (ALCL). The pts with NHL T have been treated according to BFM-90 protocol. The predominant primary site of disease was mediastinum (59.3%). Complete remission (CR) was achieved by 87%. EFS for all NHL T pts was 65% and 56% for pts with extensive tumours and 73% for pts with tumours < 10 cm. Patients with NHL B were treated according to the adopted LMB-89 protocol. The majority were Burkitts type and presented abdominal location (50%). 80% with disseminated disease. CR was achieved by 89% patients, but 94% with LDH < 500 IU/L and 73% with LDH > 500 IU. The median time of follow up was 53 months. EFS was 73% for all patients. The patients with ALCL were treated according to several protocols. Peripheral nodes were the most often primary location (40%), than mediastinum (24%) and abdomen (21%). EFS for all pts was 63%. Despite great progress in the therapy of NHL in children during 20 years of observation, the results are not satisfactory in disseminated stages. It is necessary to look for new prognostic markers which make it possible to improve classification of patients. Major surgery in advanced stages is not recommended since it delays chemotherapy and fails to improve overall survival. Early detection of neoplasm is one of the most important efforts to improve therapy success.